Fixing regression in MRTK3's Profile Editor (#11694)

The #11681 pull request removed the spatialization mixer property from the MRTK3 Profile, but neglected to remove the reference from the associated editor component.

This change removes the spatialization mixer from the editor component.  Also adding a unit test to help ensure this doesn't break again.

com.microsoft.mrtk.core/Editor/Editors/MRTKProfileEditor.cs

@@ -7,7 +7,6 @@
 using System.Text;
 using UnityEditor;
 using UnityEngine;
-using UnityEngine.Audio;
 
 namespace Microsoft.MixedReality.Toolkit.Editor
 {
@@ -188,10 +187,6 @@ private static class Styles
         // subsystem types to config ScriptableObjects.
         private SerializedProperty serializedConfigs;
 
-        // The serialized audio mixer group that is to be
-        // used when playing spatiailized sounds.
-        private SerializedProperty serializedMixerGroup;
-
         // All concrete subsystems in currently loaded assemblies,
         // which are tagged with the MRTKSubsystemAttribute.
         private SortedDictionary<string, List<SubsystemItem>> allSubsystemTypes = new SortedDictionary<string, List<SubsystemItem>>(StringComparer.InvariantCultureIgnoreCase);
@@ -218,7 +213,6 @@ private void OnEnable()
         {
             serializedSubsystems = serializedObject.FindProperty("loadedSubsystems");
             serializedConfigs = serializedObject.FindProperty("subsystemConfigs");
-            serializedMixerGroup = serializedObject.FindProperty(InspectorUIUtility.GetBackingField("SpatializationMixer"));
         }
 
         public override void OnInspectorGUI()
@@ -245,8 +239,6 @@ public override void OnInspectorGUI()
                                  + ".\nCheck the MR Feature Tool to import missing subsystems.", MessageType.Warning);
             }
 
-            DrawSelectedMixer();
-
             using (new EditorGUILayout.HorizontalScope(GUILayout.ExpandWidth(true), GUILayout.ExpandHeight(true)))
             {
                 DrawSubsystemList();
@@ -258,13 +250,6 @@ public override void OnInspectorGUI()
 
         #region Drawing methods
 
-        private void DrawSelectedMixer()
-        {
-            EditorGUILayout.ObjectField(
-                serializedMixerGroup,
-                typeof(AudioMixerGroup));
-        }
-
         /// <summary>
         /// Draws the display name, author, and full name of the specified subsystem.
         /// </summary>

com.microsoft.mrtk.core/Tests/Editor/MRTK3ProfileEditorTest.cs

@@ -0,0 +1,40 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using NUnit.Framework;
+using System.Collections;
+using UnityEditor;
+using UnityEngine;
+using UnityEngine.TestTools;
+using UnityEngine.UIElements;
+
+namespace Microsoft.MixedReality.Toolkit.Core.Tests.EditMode
+{
+    internal class MRTK3ProfileEditorTest
+    {
+        /// <summary>
+        /// Verify that the <see cref="MRTK3ProfileEditor"/> window can be opened.
+        /// </summary>
+        /// <remarks>
+        /// This test is disabled when executing in batch mode, since it requires a Unity graphic device.
+        /// </remarks>
+        [UnityTest]
+        public IEnumerator InspectorWindowSmokeTest()
+        {
+            if (Application.isBatchMode)
+            {
+                yield return null;
+            }
+            else
+            {
+                var window = SettingsService.OpenProjectSettings("Project/MRTK3");
+                Assert.IsNotNull(window, "The MRTK Profile editor window should have been opened");
+
+                var panel = window.rootVisualElement.Query<IMGUIContainer>(className: "settings-panel-imgui-container").First();
+                Assert.IsNotNull(panel, "There should have hand a settings panel created for the MRTK Profile.");
+
+                yield return null;
+            }
+        }
+    }
+}